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Biomedical subjects

Y C Wong

Publications and source records attributed to Y C Wong.

At least 19 recordsLinked to original sources
PubMed1992

Ultrastructural and cytochemical studies of the effects of prolactin on the lateral prostate and the seminal vesicle of the castrated guinea pig.

Administration of ovine prolactin to castrated guinea pigs for 2 weeks induced hypertrophy of secretory cells in the lateral prostate when compared with the castrated controls. This was accompanied by an apparent increase in the number of profiles of granular endoplasmic reticulum and well developed Golgi complexes with dilated cisternae. An increase in the number of low-contrast electron-dense secretory granules was observed 4 weeks after prolactin treatment. In the seminal vesicle, dilatation and degranulation of granular endoplasmic reticulum and an apparent decrease in the number of secretory granules were observed 4 weeks after prolactin administration. Following castration and 2 weeks after prolactin treatment, thiamine pyrophosphatase (TPPase)-reaction product was mainly confined to 1-2 trans cisternae of the Golgi complexes in secretory cells of the lateral prostate and the seminal vesicle. In both glands, a reduction of TPPase activity was observed 2 weeks following prolactin administration, and the reaction product was totally absent after prolonged treatment for 4 weeks. The present study has provided morphological evidence that prolactin is capable of stimulating the secretory function of the lateral prostate while exerting some inhibitory effects on the seminal vesicle of the castrated guinea pig. In both glands, TPPase activity, and hence the process of glycosylation was inhibited after prolactin administration. The results from radioimmunoassay indicated that the action of prolactin on these glands could be a direct effect and not mediated through testosterone.

Animals↗
PubMed1992

The use of a packed column for the determination of bupivacaine in human plasma by gas chromatography: an application in a pharmacokinetic study of bupivacaine.

The method involves a single extraction of the drug and the internal standard, etidocaine, from alkalinized plasma with n-hexane. The gas chromatograph is equipped with a glass column (2.0 m x 2 mm) packed with 3% W/W SP2250 on Chromosorb W, (80/100 mesh) and a nitrogen sensitive detector. The method can accurately measure plasma bupivacaine concentrations down to 0.01 micrograms ml-1 using a sample size of 0.5 ml. The day-to-day variation of bupivacaine at 2.0 micrograms ml-1 is 6.90% (n = 10). The calibration graph is linear over the range 0.1-4.0 micrograms ml-1. The method is accurate, fast and sensitive and has been applied in a pharmacokinetic study of bupivacaine.

Absorption↗
PubMed1992

Accuracy in diagnosis of ectopic pregnancy by transvaginal ultrasonography.

Forty patients suspected to have ectopic pregnancy by transvaginal ultrasonography had surgery. 77.5% were confirmed to have ectopic pregnancy and 10% had other abnormal pelvic findings. The transvaginal approach appears to enable us to diagnose ectopic pregnancy at an earlier date, with the earliest diagnosis made at 4 weeks 0 days of amenorrhoea. In cases of confirmed ectopic pregnancy, the presence of a complex adnexal mass was the most common feature seen on transvaginal ultrasound and its predictability of ectopic pregnancy is enhanced by a concomitant finding of an empty uterus (95%) or free fluid in the Pouch of Douglas (94%) in the presence of a positive hCG test. The significance of transvaginal ultrasound features, and the advantages of transvaginal over transabdominal ultrasound, are discussed.

Female↗
PubMed1992

Outcome of 143 pregnancies conceived by assisted reproductive techniques.

One hundred and forty-three pregnancies conceived by assisted reproductive techniques (ART) from October 1985 to June 1989 in the National University Hospital, Singapore, resulted in 66 deliveries and 89 babies. There were 27 (18.7%) biochemical pregnancies, 44 (30.7%) clinical miscarriages and 6 (4.2%) ectopic pregnancies when total pregnancies were considered. Of those who continued pregnancy to second trimester multiple births occurred in 20 (13.3%) patients. A high incidence of vaginal bleeding and hypertension in pregnancy was noted in 32 (48.5%) patients and 18 (27.3%) patients, respectively. Caesarean section was the method of delivery in 48.5% of patients. Twenty-six (29.2%) babies required admission to the neonatal intensive care unit. All babies except one set of twins delivered at 24 weeks of amenorrhoea survived. Fetal abnormality was noted in 2 cases.

Adult↗
PubMed1992

A case report: vesico-rectal fistula with ano-urethral atresia.

Vesico-rectal fistula is a rare congenital abnormality causing severe early second trimester oligohydramnios. Prenatal diagnosis of such a case is reported here. Ultrasound diagnosis could be aided by transabdominal amnio-infusion and, if necessary, fetal intraperitoneal saline installation. In a karyotypically normal fetus with normal somatic growth, demonstration of normal fetal kidneys together with a functioning urinary bladder, in presence of severe oligohydramnios, is very suggestive of the diagnosis. Since pulmonary hypoplasia is the major cause of neonatal mortality in these cases, restoration of normal amniotic fluid volume by serial amnio-infusion was attempted. Although amnio-infusion is an important diagnostic aid in the evaluation of severe midtrimester oligohydramnios, the role of multiple therapeutic amnio-infusion in improving lung growth remains to be evaluated.

Abnormalities, Multiple↗
PubMed1992

Amniocentesis and its complications.

This study was conducted in order to evaluate whether the performance of an experienced operator had any significant influence in reducing the incidence of complications in amniocentesis; 1,459 women had amniocentesis performed under ultrasound guidance; 1,324 were performed by experienced operators and 135 cases by less experienced operators. Complications like fetal loss, blood-stained amniotic fluid, culture failure, multiple needle puncture, leaking liquor, fetal trauma and error in results were compared in the 2 groups. This study demonstrated that amniocentesis performed by an experienced operator decreased the various complications associated with amniocentesis.

Amniocentesis↗
PubMed1992

Localization of prostatic glycoconjugates by the lectin-gold method.

The glycoconjugates of the lateral prostate were examined ultrastructurally by lectin-gold histochemistry in combination with a low-temperature embedding technique using Lowicryl K4M. The binding patterns of concanavalin A, wheat germ agglutinin, Griffonia simplicifolia, soybean agglutinin, peanut agglutinin, Ricinus communis agglutinin isolectin I, Griffonia simplicifolia isolectin B4, Ulex europaeus isolectin I and Phaseolus vulgaris agglutinin P have been documented in the subcellular compartments of the lateral prostate. The results show that the granular endoplasmic reticulum (GER) is rich in glycoproteins with mannosyl residues while the Golgi cisternae, secretory granules and microvilli are less so. The mannose (Man) and N-acetylglucosamine (GlcNAc) residues present in the GER of the epithelial cells may be associated with the initial assembly of the N-linked oligosaccharides of glycoproteins. The secretory granules exhibited different reactivities to lectins. Most of the lectin-binding sites confined to the limiting membranes may play a role in the transport of plasmalemma glycoconjugates to the apical plasma membrane. The epithelial Golgi stack is rich in GlcNAc, galactose (Gal), N-acetylgalactosamine (GalNAc) and sialic acid residues, and a compartmental organization of the Golgi stack is apparent which might be associated with the sequential addition of sugar residues to the oligosaccharides. The plasma membrane contains abundant Man, GlcNAc, Gal, GalNAc and complex carbohydrates, especially in the microvilli, and a differential lectin labelling was noted between the apical and basolateral plasma membrane. The present study showed that fucose-containing glycoconjugates were detected in the apical plasma membrane of the lateral prostate. The stromal extracellular matrices as well as the epithelial basement membranes demonstrated weak lectin reaction. Man, GlcNAc, Gal residues and complex sugars were also noted in the stromal tissues of the lateral prostate including the extracellular matrix, capillaries and smooth muscle.

Animals↗
PubMed1992

Effects of mesenchyme of the embryonic urogenital sinus and neonatal seminal vesicle on the cytodifferentiation of the Dunning tumor: ultrastructural study.

The aim of the present study was to examine the effects of mesenchyme on the cytodifferentiation of the Dunning tumor (DT, R3327), a transplantable rat prostatic adenocarcinoma developed spontaneously from the dorsolateral prostate of a Copenhagen rat. Small pieces of DT were combined with mesenchyme of the rat urogenital sinus (18-day fetal, UGM) or seminal vesicle (0-day neonatal, SVM). Both types of combinations were grown under the kidney capsule of male athymic nude mice for 4 weeks. At harvest, the tissue recombinants were fixed and processed for electron microscopy. Grafts of parental DT were similarly processed for electron microscopy. The tumor was characterized by tubules lined by 2-3 layers of undifferentiated cells lacking secretory granules. The basal lamina was reduplicated, and epithelioid cells traversing gaps in the basal lamina were frequently observed. The stroma was composed of a mixture of fibroblastic and large epithelioid cells derived from the ductal lining epithelium through a process of micrometastasis. In UGM or SVM+DT combinations the mesenchyme influenced the differentiation and secretory activity of the DT epithelium. The induced DT epithelial cells exhibited a well-developed granular endoplasmic reticulum, a large Golgi apparatus and prominent secretory granules which were never observed in the parental DT. The basal lamina returned to normal, while the incidence of micrometastasis was decreased. The collagen content of the stroma was increased with a concurrent appearance of smooth muscle cells surrounding those tubules where secretory cytodifferentiation had occurred. While the mechanism involved in the mesenchyme-induced change in cytodifferentiation remains unknown, it is evident that the DT epithelial cells when associated with normal embryonic or neonatal mesenchyme can express a more normal cytodifferentiation and function. It is concluded (a) that the DT cells can be induced by mesenchyme to express more highly differentiated ultrastructural patterns and secretory cytodifferentiation, (b) that the induced secretory cytodifferentiation is associated with a reduction in invasiveness (micrometastasis) and a more normal-appearing basal lamina and (c) that the increased abundance of collagen fibers and the differentiation of smooth muscle in the stromal compartment are associated with secretory cytodifferentiation suggesting that reciprocal epithelial-mesenchymal interactions are involved in the regulation of the pathobiology of the DT.

Adenocarcinoma↗
PubMed1992

Morphometric and stereological study of the seminal vesicle of the guinea pig.

The seminal vesicle of the guinea pig has been widely used as a model for the study of hormonal action on the male accessory sex organ, but there have been few attempts to quantify their cellular and tissue components. In the present study, the seminal vesicle of the guinea pig was described in the form of a morphometric model. Tissue samples were taken from the distal, middle and proximal regions of the gland and processed for light microscopy. Using a combination of a stereological point-counting technique and direct measurement, the relative volumes of different components (lumen, epithelium, lamina propria and fibromuscular layer) were determined. The relative numbers of the secretory cells and basal cells were also estimated. Following the estimation of the average size of the seminal vesicle, the relative volume of different components and the relative number of secretory cells were transformed into absolute data on a per average seminal vesicle basis. Similarly, the average sizes of the secretory cells and nuclei were also determined. The quantitative data generated from the present study will serve as a baseline for further studies of the seminal vesicle of the guinea pig. The techniques used in the present study are easy to apply, and data generated were objective and reproducible.

Animals↗
PubMed1992

Cytochemical localisation and characterisation of proteoglycans (glycosaminoglycans) in the epithelial-stromal interface of the seminal vesicle of the guinea pig.

The proteoglycans (PGs) in the guinea pig seminal vesicle were demonstrated ultrastructurally by both cuprolinic blue (CB) and ruthenium red (RR) staining. The PGs appeared as electron-dense granules with RR, but were filamentous following CB staining using the critical electrolyte concentration method. Three major types of PGs (T1, T2, T3) have been described according to their different locations and sizes. T1 filaments were short and were found mostly on both sides of the lamina densa of the basal lamina of the glandular epithelium (40-60 nm long) and also on the basal laminae of smooth muscle cells and capillary endothelial cells (20-30 nm long). In the epithelial basal lamina they were regularly spaced at an interval of 40-60 nm. T1 filaments in the lamina densa were smaller and more randomly distributed. Cytochemical characterisation of these PGs by various GAG degrading enzymes showed that T1 PGs are rich in heparan sulphate. T2 filaments were 30-40 nm long and closely associated with the collagen fibrils. They were arranged perpendicular to the long axis of collagen fibrils, also at intervals of about 60 nm. T2 filaments were removed by chondroitinase (Ch)-ABC, Ch-ABC plus Streptomyces (S)-hyaluronidase and pronase, but resistant to nitrous acid, heparitinase, heparinase, neuraminidase and S-hyaluronidase. These show that T2 filaments are rich in dermatan sulphate. T3 filaments (60-100 nm) were widely distributed in the stroma at sites such as the interstitial spaces of the lamina propria, the reticular layer below the basal lamina, around individual collagen fibrils or bundles of such fibres, and on the cell surfaces of fibroblasts. The T3 filaments were removed by Ch-ABC, Ch-AC and pronase but were resistant to heparitinase, heparinase, S-hyaluronidase, neuraminidase and nitrous acid. They are therefore rich in chondroitin sulphate.

Animals↗
PubMed1992

Umbilical artery blood flow in intra-uterine growth retarded fetuses and fetal outcome: a study of 102 cases.

The 102 fetuses diagnosed by ultrasound to be asymmetrically growth-retarded had blood flow velocity waveforms of the umbilical artery studied. Sixty-two cases had normal blood flow, 28 had abnormal blood flow but with present end-diastolic flow, 8 had absent end-diastolic flow, and 4 had reversal of end-diastolic flow. Comparison was made between the blood flow status and other biophysical methods of antenatal surveillance and perinatal outcome. There is a strong correlation between abnormal blood flow and abnormalities detected by other biophysical methods of antenatal surveillance. Our study shows that fetuses with severe blood flow impairment tend to be more severely growth-retarded and to be delivered earlier. Our results also show abnormal blood flow to be associated with a poor perinatal outcome. Those fetuses with severe impairment of blood flow suffered a high incidence of operative delivery for fetal distress, acidosis at birth, perinatal mortality and morbidity. The association between abnormal blood flow and the 5-minute Apgar score is significant only in those with the severest impairment of blood flow. Our results are in close agreement with similar studies recorded in the literature.

Apgar Score↗
PubMed1991

Expression of enhancer binding factors associated with various cell types of lung cancer.

Differential expression of nuclear factors binding specifically to AP-1, AP-2, AP-3, and NF-I/CTF enhancer elements was found in the various cell types of human lung carcinoma cells. Adenocarcinoma and squamous carcinoma cells seemed to express higher levels of these factors than large-cell carcinoma and small-cell carcinoma cells. Among small-cell carcinoma cells, variant small-cell carcinoma cells which presumably are closer than classical small-cell carcinoma cells to non-small-cell carcinoma cells in terms of differentiation characteristics also expressed higher levels of these factors. Furthermore, nuclear extracts from the various cell types of carcinoma cells were found to produce different patterns of electrophoretic mobility shift even with the same enhancer element, suggesting the presence of multiple species of specific enhancer-binding activities in these cells. Thus, these enhancer elements may be used as probes for cell-type specificity in the study of differentiation of lung carcinomas.

Adenocarcinoma↗
PubMed1991

Determination of pethidine and its major metabolites in human urine by gas chromatography.

Procedures based on gas chromatography were established to determine pethidine and its major metabolites in human urine. The chromatographic system consisted of a glass column packed with 3% (w/w) SP2250 on Chromosorb W (80-100 mesh) linked to a nitrogen-phosphorus detector. Diethyl ether was used as the extraction solvent. Pethidinic and norpethidinic acids, and their conjugated metabolites (after beta-glucuronidase treatment) were determined after conversion into pethidine and norpethidine by acid-catalysed esterification. The retention times of pethidine, norpethidine and chlorpheniramine (internal standard) were 3.3, 4.5 and 7.5 min, respectively. The amount of unchanged drugs and metabolites excreted varied considerably among the subjects. The mean 24-h urinary recoveries in eight patients of pethidine, norpethidine, pethidinic acid, norpethidinic acid, and the glucuronides of pethidinic and norpethidinic acids were 6.62 +/- 5.05, 4.33 +/- 1.19, 18.9 +/- 6.29, 9.10 +/- 4.26, 15.1 +/- 3.02 and 7.57 +/- 2.28%, respectively. This indicates that the major metyabolic pathways of pethidine in the eight patients were hydrolysis followed by conjugation. Over 60% of the dose was accounted for in 24 h after intramuscular administration of 1 mg/kg pethidine.

Chromatography, Gas↗
PubMed1991

Morphometric and stereological study of the glandular epithelium of the lateral prostate of the intact and castrated guinea pig.

The glandular epithelium of the lateral prostate of the guinea pig was described within the framework of a morphometric model in terms of relative densities and absolute dimensions. A combination of direct measurement and point and intersection counting techniques was used. The quantitative data generated in the intact animals were compared with those of castrated controls. Castration was accompanied by a significant decrease in height of the glandular epithelium and in sizes of secretory and basal cells and their corresponding nuclei. On a per cell basis, significant decreases in total volume and surface area of granular endoplasmic reticulum were detected after castration. This was accompanied by a significant reduction in the total volume of Golgi cisternae. The total volume, surface area, and number of highly electron-dense and clear granules decreased significantly compared with the intact control animals. However, no significant changes in these parameters of low electron-dense granules were found. Significant reductions in the total volume and surface area of condensing granules, lysosomes, and mitochondria, but not their number, were detected. The average sizes of condensing granules, secretory granules, lysosomes, and mitochondria were decreased significantly after castration. The present study showed that the alterations in the secretory function of the secretory cells of the lateral prostate was reflected by the quantitative changes in granular endoplasmic reticulum, Golgi complexes, and secretory granules on a per cell basis. The data generated in the present study will serve as a baseline for further studies of the lateral prostate of the guinea pig.

Animals↗
PubMed1991

Glycoconjugates of the lateral prostate of the guinea pig: a lectin histochemical study.

The present study examined the glycoconjugates of the lateral prostate using a battery of lectins. The results indicated that the secretory epithelium was rich in mannose (Man), N-acetylglucosamine (GlcNAc), galactose (Gal), N-acetylgalactosamine (GalNAc), and complex oligosaccharides. Con A (concanavalin A), LCA (Lens culinaris agglutinin), PSA (Pisum sativum agglutinin), WGA (wheat germ agglutinin), PWM (pokeweed mitogen), RCA-I (Racinus communis isolectin I), and PHA-P (Phaseolus vulgaris agglutinin-P) reacted intensely with both epithelia and stroma, while SBA (soybean agglutinin) and PNA (peanut agglutinin), which bind to terminal Gal, GalNAc, and Gal beta 1,3 GalNAc appeared to be specific to the secretory epithelium. SBA and PNA were useful as markers in the study of the secretory function of the prostate gland. The present study has shown that the Golgi apparatus of prostatic epithelial cells was rich in fucose (Fuc), oligomers of GlcNAc, Gal beta 1,3 GalNAc, Gal, and Man containing glycoconjugates, indicating that the gland was actively involved in glycosylation. The present study has also shown that LTA (Lotus tetragonolobus agglutinin) is a good marker for the epithelial Golgi. PNA also bound to the epithelial basement membrane and the connective tissue in the lamina propria. The present study has thus established, for the first time, the glycoconjugate patterns in the lateral prostate of the guinea pig.

Acetylgalactosamine↗
PubMed1991

Morphometric and stereological analysis of the effects of 17 beta-estradiol on the glandular epithelium of the castrated guinea pig lateral prostate.

Upon administration of pharmacological doses of estradiol to castrated guinea pigs, the secretory cells of the lateral prostate underwent hypertrophy which resulted from significant increases in nuclear and cytoplasmic volume. There were quantitative increases in the small highly electron-dense granules and multivesicular bodies when compared with the castrated control. The dramatic increase in the number of highly electron-dense granules probably occurred at the expense of the low electron-dense granules. The average size of the condensing granules and mitochondria decreased significantly after estradiol administration. However, significant increase in the number of mitochondria was detected when compared with the castrated control. Ultrastructural data revealed no significant changes in the absolute dimensions of granular endoplasmic reticulum or of the Golgi complex, suggesting that estradiol exerted no significant stimulatory effects on these organelles. Pharmacological doses of estrogen appear to regulate the expression of secretory granules and multivesicular bodies in the lateral prostate of castrated guinea pigs.

Animals↗
PubMed1991

Ultrastructural study of the effects of 17 beta-oestradiol on the lateral prostate and seminal vesicle of the castrated guinea pig.

Administration of oestradiol to castrated animals induced hypertrophy of the secretory cells in the lateral prostate and seminal vesicle. In the lateral prostate, increases in the number of small highly electron-dense granules, multivesicular bodies and intercellular spaces were the prevailing effects 2 weeks after oestradiol treatment. There was also an apparent increase in the amount of cytokeratin intermediate filaments. Prolonged oestradiol administration for 4 weeks showed no appreciable changes in the glandular epithelium when compared with 2-week treatment. However, an increase in the thickness of the fibromuscular layer was observed. In the seminal vesicle, basal cell hyperplasia was associated with a concurrent increase in the size of intercellular spaces 2 weeks after oestradiol administration. There were also apparent increases in the volume of the lamina propria and in the number of stromal cells. An apparent increase in the density of collagen fibres in the stroma was observed 2 and 4 weeks after oestradiol administration. In conclusion, the responses of the epithelium of the lateral prostate and seminal vesicle to a pharmacological dose of oestradiol are different. Prolonged oestradiol administration exerts a more prominent effect on the smooth muscle in the lateral prostate but not in the seminal vesicle. The effects of oestradiol may be mediated directly or indirectly through the other hormones.

Animals↗